1. Field of the Invention
The present invention relates to ophthalmological apparatuses.
2. Description of the Related Art
For the purpose of early diagnoses of lifestyle-related diseases and high-ranked diseases causing blindness, eye fundus examinations have been widely performed. A scanning laser ophthalmoscope (SLO) that is an ophthalmological apparatus based on the principle of confocal laser scanning microscopy performs raster scanning of laser which is measurement light onto an eye fundus to quickly acquire a high resolution planar image from the intensity of its return light. In recent years, an adaptive Optics SLO (AO-SLO) has been developed which has an adaptive optical system configured to measure in real time the aberration of an eye to be examined with a wave-front sensor and correct the aberration of measurement light or its return light occurring in the eye to be examined with a wavefront correction device and thus allows acquisition of a planar image having high traverse resolution. Moreover, it has been attempted that an image of cones in the retina is extracted by using the acquired planar image of the retina, and its density or distribution is analyzed for disease diagnosis or drug response assessment.
Assessment of the advancement of a disease or changes of cones due to a drug response may require serial observation of an acquired AO-SLO image. Japanese Patent Laid-Open No. 2012-16620 discloses means for performing alignment in a depth direction to compare tomographic images of an eye fundus acquired over time. Japanese Patent Laid-Open No. 2010-220771 discloses a display method which juxtaposes tomographic images and eye fundus images acquired over time and shows a correspondence relationship. Japanese Patent Laid-Open No. 2008-29732 discloses a display method which presents a lesion position detected on an eye fundus image acquired earlier on an eye fundus image acquired subsequently of eye fundus images acquired over time.
Comparison of cones on temporally sequential AO-SLO images may require a comparison of changes in density or turbulences of an alignment state of cones which are handled as a group. For that, the region of interest for comparison must have an identical shape at an identical position on AO-SLO images acquired over time. When a plurality of AO-SLO images are acquired over time, a region of interest may be selected from regions included in all of the acquired AO-SLO images or an AO-SLO image partially not including a selected region is excluded from the comparison subjects. This processing, however, has a problem that an AO-SLO image to be compared with the selected region of interest may not be identified easily. This problem of such temporal comparisons has not been pointed out in the prior arts.